Saturday, May 3, 2008

DNA Paternity Tests: What Are They?

DNA paternity tests are used to determine if a man is in fact the biological father of a child and are done to either determine or to rule out paternity. These tests can even be done before the baby is born if necessary, although there may be a slight risk to the fetus, so in most instances, it is recommended and preferred to wait until after birth for testing. Postnatal paternity tests pose absolutely no risk at all to the infant and can be conducted at any time after birth.
Photo: renjith krishnan

DNA Paternity Tests Explained

Deoxyribonucleic acid, or DNA as it is most commonly referred to as, is an extremely vital molecule that is found in every living thing on earth. DNA contains the basis of our heredity and dictates which particular traits are passed on from one generation to the next.

Human DNA resembles a tightly coiled double helix, or more simply, a twisted ladder. The two sides of the ladder are comprised of four bases and the "rungs" are hydrogen bonds which connect the bases to one another. The way the molecules are arranged is referred to as the DNA sequence, which in essence, is a detailed list of instructions that dictate the specifics of physical characteristics found within our genes.

For testing purposes, chemical agents are used to extract the DNA from the samples collected and a profile is created using a complex process that detects what are known as loci, or locations, on the DNA helix. The testing continues as each loci is detected through a molecular replicating process that is used to create a "map" of the DNA's loci which is referred to as the DNA profile.

If half of the loci from the child's sample are found to match those from the alleged father, paternity is established and he is determined to be the biological father. If three or more loci do not match those from the alleged father's sample, he is excluded from paternity. Depending on the specific markers that don't match the child's, further testing may be done to ensure that the results are conclusive and completely accurate.
Photo: jscreationzs

Different Types of DNA Paternity Tests

There are two methods commonly used to collect DNA samples for postnatal paternity testing. Also referred to as a "cheek swab," the buccal sample collection method is completely painless and involves swabbing the inside of the cheek with a large cotton swab that contains special fibers which allows the DNA to adhere to it.

The "pin prick" method involves a small lancet that's used to prick the finger to collect a small amount of blood that's transferred to a collection card, which is then used to test the DNA. It's usually recommended that children under the age of 8 have their blood samples collected by a qualified physician, or to simply use the buccal swab method instead.

It is even possible for paternity to be established using the DNA of the alleged father's parents if he is missing, deceased, or otherwise unavailable for testing. In this instance, samples from both of the man's parents will then need to be collected and tested.